1. Field of the Invention
The present invention relates to methods and systems of achieving high precision gap and orientation measurements in imprint lithography.
2. Description of the Relevant Art
Imprint lithography is a technique that is capable of printing features that are smaller than 50 nm in size on a substrate. Imprint lithography may have the potential to replace photolithography as the choice for semiconductor manufacturing in the sub-100 nm regime. Several imprint lithography processes have been introduced during 1990s. However, most of them have limitations that preclude them from use as a practical substitute for photolithography. The limitations of these prior techniques include, for example, high temperature variations, the need for high pressures and the usage of flexible templates.
Imprint lithography processes may be used to transfer high resolution patterns from a quartz template onto substrate surfaces at room temperature and with the use of low pressures. In the Step and Flash Imprint Lithography (SFIL) process, a rigid quartz template is brought into indirect contact with the substrate surface in the presence of light curable liquid material. The liquid material is cured by the application of light and the pattern of the template is imprinted into the cured liquid.
Imprint lithography processes can be used to manufacture single and multi-layer devices. Single layer devices, may be manufactured by forming a thin layer of material into desired features on a substrate. To produce devices having a feature size below 100 nm, an imprinted layer thickness may be less than ¼ of the mean wavelength of a broadband light. The imprinted layer should also be substantially planar. Thus, it is desirable to have accurate and rapid methods of measuring the gap and the orientation between a template and a substrate during an imprint lithographic process.
More specifically, for the purpose of imprint lithography, gap and orientation measurement processes need to facilitate gap measurement in the range of less than 10 nm to 30 μm. Gap measurements, therefore, should be achieved without contacting the template and substrate and with a resolution of less than 10 nm.